RadioShack previously lowered its asking prices for the iPhone 5 by a cool $25, but that was only for the AT&T version of the popular handset. Sweetening its holiday deal, the American franchise of electronics retail stores has now shaved $50 off both the iPhone 4S and iPhone 5, regardless of your preferred carrier. The retailer is basically price-matching Best Buy’s promotion where they also knocked $50 off all iPhone 5 models. Go past the fold for additional terms and conditions…

RadioShack’s deal lets you get a 16GB iPhone 5 on AT&T, Verizon or Sprint for as low as $149. Even better, you could buy an iPhone 4S for just $49.

Note a two-year contract is required for the RadioShack deal, which is valid for in-store purchases only.

We have no idea when the promotion is set to expire, but you’ll get a $10 cash back for every $50 spent at RadioShack until December 17, in addition to free ground shipping for orders over $50.

Both RadioShack’s and Best Buy’s deal let you buy – for a limited time, of course – the lowest-cost iPhone 5 anywhere in the US, unless I’m mistaken.